Signal.



C. O. HARRINGTON.

SIGNAL.

APPLICATION HLED MAY 11. 1915.,

1,202.16. Patented Oct. 24,1916.

I I. INVENTOR} I TED STATES PATENT OFFICE.

CLINTON O. HARRINGTON, OF EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A COR- PORATION OF PENNSYLVANIA.

SIGNAL.

Specification of Letters Patent.

Patented Oct. 24, 1916.

Original application filed July 12, 1913, Serial No. 778,783. Patent No. 1,157,102, dated October 19, 1915.

Divided and this application filed May 11, 1915. Serial No. 27,345. i

-Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Signals, of which the following is a specification.

My'invention relates to signaling, and particularly to apparatus for controlling signals of the type-in which... lamps are employed for giving indications both in daylight and at night.

My invention is particularly adaptable for use in connection with railway signals.

The present applicationis a division of I .my co-pending application, Serial Number 778,783, filed July 12, 1913, for signals.

I will describe one form of controlling apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing I have shown a view, partly diagrammatic, of one form of signal having associated therewith one form of controllingapparatus embodying my invention.

When a lamp is employed as a signal for giving indications both in daylight and at night, such for example as a railway signal,

' -the lamp must, during daylight, be illuminated at such intensity as to be clearly visible during the brightest sunlight and under the worst conditions of relative position of the sun and the signal, viz., when the signal is directly between-the sun and the observer, or when the observer is directly between the signal and the sun. But it is undesirable that this high intensity of illumination be maintained at night because the light from the lamp would then be dazzling to the observer, and the observation at frequent intervals of a successlon, of slgnals comprising such lamps would have an undesirable physiological effect on the observer.

It is thereforedesirable that the lamps in such signals should be illuminated at one intensity for daylight indications and a lower intensity for 'night indications.

One feature of my invention is the provision of means for causing the illuminatlon v of the lamps in such signals at one intensity for daylight indications and at a lower intensity for night indications.

Referring to. the drawing, S designates a signal which may be a railway signal, comprising two electric incandescent lamps G and R which lamps are provided respectively with lenses 2 and 2 for projecting the light from the lamps in beams along the trackway. These lamps are employed for giving indications both in daylight and at night. The light projected from the two lamps usually differs in color, the light from lamp G usually being green and that from lamp R red; this coloring of the light may be effected in several different ways, for example, by forming the lenses 2 and 2 of green and red glass respectively. The representation of signal S being diagrammatic, the casing in which the parts are usually inclosed is omitted for the purpose-of simplifying the drawing.

Lamps G and R are provided with circuits which include a source of current 3, here shown as being a direct current battery.

These circuitsare controlled by an armature contact 4 of an electromagnetic relay 4,. which may, for example, be a track relay in a railway signaling system; the control being such that when the relay is energized, so

this resistance 5. The voltage'at the lamps.

G and R, and consequently the intensity ofillumination of these lamps, varies according as thelow resistance shunt is open or closed. This shunt is opened and closed by a relay device L which is responsive to. variations of intensity of external light and which I will now explain. 7

N and S designate the two poles of a dynamometer, between which is located a pivotally mounted armature 21. This armature 21 is provided with two windings 22 and 23 (each represented diagrammatically by a single turn of wire) both of which windings are constantly energized from a source of current 19, here shown as being a battery. The torques exerted on armature 21 by currents in these two windings are in opposite directions, that exerted by current in winding 22 being in the direction of the arrow, and that exerted by current in winding 23 being in the opposite direction, The circuits for the two windings are in multiple and include respectively a resistance 20 and a resistance 20*. These .resistances have the same percentage of variation of resistance per degree of change oftemperature, or in other words, the ratio of their resistances remains-the same regardless of changes of temperature provided the changespf temperature of the two resistances are equal. Preferably the two resistances are of, the same material. Means are provided for causing unequal variations of these resistances due to variations of intensity of external light; as here shown, this is accomplished by polishing resistance 20 and blackening resistance 20. Hence, when a given amount of light is falling on both resistances, resistance 20 will absorb more light than resistance 20 and the temperature of the former will,therefore, be higher than that of the latter, so that the resistance of the former will be higher than that of the latter. The current in winding 22 will then be greater than that in winding 23 so that a torque Willbe exerted on armature 21 in the direction of the arrow. Fixed to arma- 'ture 21 to move therewith is a contact arm' 24, the outer end of which is adapted to move into'and out of engagement with a con tact point 25. The armature 21 is biased by a spring 27 to such position that arm 24 is in engagement with a fixed stop 26, in which position contact 24--25 is open. The low resistance shunt around lamp resistance 5 c0mprises wire 13, contact 2425 and wire 14.

The relay device L is so adjusted that at night and in dim daylight the values of the currents in windings 21 and 23 are such that the torques exerted on.armature 21 are substantially equal, so that arm 24 is then held against stop 26 by spring 27, and contact 24-25 is open. The circuit for green lamp G (assuming relay 4 is closed as" shown) is then from battery 3, through relay contact 4.4 lam G, wire 32, resistance 5 to battery 3. I? relay 4 were denergized so that contact 4 '4 is closed,the circuit would be the same as just traced except that it would include lamp R instead of lamp G. The efiect of resistance 5 is to cause the current in the circuit to be of such value that whichever lamp G or R is included in circuit is illuminated at a comparatively low intensity, this intensity be ing such that the rays from the lamp are ing 23 by an amount sufficient to overcome the action of spring 27 and the armature 21 then moves and closes contact 2425. The shunt around resistance 5 is then closed, so that whichever lamp G or. R is in circuit is illuminated at its highest intensity.

Although I have herein shown and described only one form of controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims, without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: j

1. In combination, a signal comprising a lamp employed for giving indications both in daylight and at night, two electrical conductors whose electrical resistances vary in different degrees in response to variations of ordinary light, and means controlled by relative variations of the resistancesof said conductors for varying the intensity of illumination of said lamp. 2. In combination, a signal comprising a lamp employed for giving indications both in daylight and at night, two electrical conductors one of which is blackened and the other of which is polished, and means controlled by relative variations of the electrical resistances of said conductors in response to variations of external light for Irarying the intensity of illumination of said amp.

3. A relay device comprising two differential windings, a circuit for each winding, a conductor included in each circuit, said conductors having the same thermal co-eflicients, and means for causing the resistance of said conductors to be affected by ordinary light in difi'erent degrees.

4. A relay device comprising two difierential windings, a circuit for each winding, a conductor included in each circuit, said conductors having the same thermal co-efiicients, and means for causing the resistances of said conductors to be afl'ected in different degrees by variations in the intensity of ordinary' light.

5. In combination, a signal comprising a lamp employed for giving indications both in daylight and at night, a circuit for said lamp including a resistance, a shunt for said resistance, and means for controlling said shunt; said means comprising an electrodynamometer, the armature of which comprises two windings adapted to exert torques in opposite directions, two electrical conductors, one of which is blackened and the other of which is polished, connected respectively in series with said windings and means for supplying current to said windings.

6. In combination, means for producing a magnetic field, an armature located in said field and comprising two windings arranged to, exert torques in opposite directions, a circuit for each winding, a conductor included in each circuit, saidconductors having the same thermal co-eflicients, and means for causing the resistance of said conductors to be aflected by ordinary light in difi'erent degrees.

In testimony whereof I affix my signature in presence of two witnesses.

CLINTON O. HARRINGTON. 

